Dental laser systems typically use a hand piece for directing laser light or cooling fluids to an oral treatment area. Lasers can be useful in several hard and soft tissue dental procedures, including: removing decay, cutting, drilling or shaping hard tissue, and removing or cutting soft tissue.
A tooth has three layers. The outermost layer is the enamel which is the hardest and forms a protective layer for the rest of the tooth. The middle and bulk of the tooth is made up of the dentin, and the innermost layer is the pulp. The enamel and dentin are similar in composition and are roughly 85% mineral, carbonated hydroxyapatite, while the pulp contains vessels and nerves which are sensitive to pressure and temperature. Hydroxyapatite absorbs laser light in the 9.3-9.6 μm wavelength range more efficiently than radiation in any other wavelength range. Absorption of the laser energy can increase the temperature of any of the layers of the tooth. In cutting, contouring, or conditioning the enamel and dentin, it is beneficial to account for the pulp's temperature sensitivity because a rise in temperature of about 5.5° C. can lead to permanent damage of the tooth's pulp.
Lasers have been found to be useful in the removal of dental material without the use of local anesthetic similar to that required when the procedure is performed with a conventional drill. Moreover, lasers do not make the noises and vibrations that are associated with dental drills. For these reasons it has been the hope of many in the dental industry that lasers may replace the drill and alleviate, at least to some extent, the anxiety and fear from dental treatment.
Unlike dental drills a dental laser is an end cutting device, i.e., material is generally removed from the end of a focused laser beam. In contrast, a drill is side cutting device, i.e., the material is milled away by the side of the burr. The general inability of a laser device to side cut similarly as a drill can be a limitation in the use thereof. Therefore, an agile hand piece may be useful to make the many dental surfaces and locations accessible for laser treatment in order to make the use of laser technology in dentistry practical. Difficulty often arises in reaching the different treatment areas with only one hand piece tip or a hand piece that cannot fully rotate. During treatment, a required amount of coolant must also be delivered to a selected target area so as to avoid an excessive rise in the temperature thereof.
The effectiveness of the laser in treatment can depend on a number of variables. For example, the frequency and pulse width of the laser pulses typically determine the average power of the laser; a controlled volume of the flow of a coolant to the treatment area can prevent over heating of the pulpal chamber and/or melting of enamel and may also minimize power losses from attenuation of the delivered laser energy by absorption in the coolant. Setting these variables to suitable values and controlling them throughout a procedure can be beneficial to dental treatment.
Conventional dental treatment systems, such as pneumatic and electric drills, often include a foot pedal using which an operator can control the rotational velocity and/or power of the burr, allowing material removal rates to be varied throughout the procedure without needing to pause the procedure to adjust power settings. In laser-based dental systems a foot pedal may be used to actuate the firing of the laser as well as to actuate or stop the flow of the coolant. A desired laser power is usually first set by the operator, and then the laser can be fired by depressing the foot pedal or turned off by releasing the pedal. If any parameter of the treatment is to be changed, the procedure is typically suspended, the operator may adjust one or more system parameters, and may then resume the procedure. A pulse rate of the laser is one parameter that can be controlled to control the amount of laser energy delivered to the treatment area. Controlling only the pulse rate, however, is not effective in many treatment procedures.
Various presently used laser-based dental treatment systems have several additional disadvantages. For example, these systems generally require a dedicated hand piece, and do not support the use of interchangeable hand pieces. Various hand pieces commonly used do not simultaneously deliver both laser pulses and coolant. Moreover, the hand pieces are typically not rotatable so that an operator can direct laser energy to any selected location of the tooth or gum, without causing significant discomfort to a patient. Therefore, improved laser-based treatment systems and methods are needed.